[Federal Register Volume 60, Number 74 (Tuesday, April 18, 1995)]
[Proposed Rules]
[Pages 19383-19385]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-9470]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-29-AD]
Airworthiness Directives; Fokker Model F28 Mark 0100 Series
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Fokker Model F28 Mark 0100
series airplanes. This proposal would require a one-time operational
test of the No. 1 pitot heating system, and repair or replacement of
failed elements. This AD also would require modification of certain
electrical wiring, and replacement of the pitot head and a certain
relay. This proposal is prompted by reports indicating that the No. 1
Air Data Computer (ADC #1) failed due to icing of the No. 1 pitot tube.
The actions specified by the proposed AD are intended to prevent icing
of the No. 1 pitot tube, which could result in failure of the No. 1 ADC
or output of erroneous airspeed data to all on-side subsidiary systems
including the Automatic Flight Control and Augmentation System (AFCAS).
DATES: Comments must be received by May 30, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-29-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street,
Alexandria, Virginia 22314. This information may be examined at the
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
[[Page 19384]] FOR FURTHER INFORMATION CONTACT: Timothy Dulin,
Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (206) 227-2141; fax (06) 227-1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 95-NM-29-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 95-NM-29-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Rijksluchtvaartdienst (RLD), which is the airworthiness
authority for the Netherlands, recently notified the FAA that an unsafe
condition may exist on certain Fokker Model F28 Mark 0100 series
airplanes. The RLD advises that it received reports indicating that the
No. 1 Air Data Computer (ADC #1) failed on Model F28 Mark 0100 series
airplanes. This failure resulted in the loss of the captain's airspeed
indicator and malfunction alerts from all on-side subsidiary systems
[i.e., Flight Control Computer (FCC #1), Auto Throttle (AT #1), Yaw
Damper (YD #1) and Horizontal Stabilizer Trim (Stab Trim #1)].
Subsequent investigation revealed that one of two heating elements (the
tube part) of the No. 1 pitot tube had failed, which resulted in icing
of the tube. Because the electrical current level of a single
functioning element (100W) was higher than the trigger level of the
pitot heat fault alert (42W), the failure was not annunciated. In
severe icing conditions, operation of a single element produces too
little heat to prevent freezing of the pitot probe. If an undetected
heating element failure does not lead to a failure of ADC #1, erroneous
data could be supplied to those on-side subsidiary systems mentioned
above. This may cause the Automatic Flight Control and Augmentation
System (AFCAS) to generate control commands based on incorrect airspeed
data. Icing of the No. 1 pitot heat system, if not corrected, could
result in failure of the ADC #1 or lead to erroneous data being
supplied to all on-side subsidiary systems.
Fokker has issued Service Bulletin SBF100-30-015, Revision 2, dated
January 25, 1995, which describes procedures for accomplishing an
operational test of the No. 1 pitot heating system. The service
bulletin also describes procedures for removal of the DC current-
sensing relay and replacement with two new DC current-sensing relays;
the replacement of the pitot head with a new pitot head; and
modification of certain electrical wiring of the pitot heating system.
Accomplishment of this service bulletin will prevent the pitot head
from accumulating ice due to failure of a heating element in the No. 1
pitot tube. The RLD classified this service bulletin as mandatory and
issued Netherlands airworthiness directive BLA 94-114(A), dated August
5, 1994, in order to assure the continued airworthiness of these
airplanes in the Netherlands.
This airplane model is manufactured in the Netherlands and is type
certificated for operation in the United States under the provisions of
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and
the applicable bilateral airworthiness agreement. Pursuant to this
bilateral airworthiness agreement, the RLD has kept the FAA informed of
the situation described above. The FAA has examined the findings of the
RLD, reviewed all available information, and determined that AD action
is necessary for products of this type design that are certificated for
operation in the United States.
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design registered
in the United States, the proposed AD would require a one-time
operational test of the No. 1 pitot heating system, and repair or
replacement of failed elements. This AD also would require modification
of certain electrical wiring, replacement of the pitot head with a new
pitot head, and replacement of the single DC current-sensing relay with
two new DC current sensing relays. Certain actions would be required to
be accomplished in accordance with the service bulletin described
previously. Repair or replacement of any failed elements would be
required to be accomplished in accordance with the Aircraft Maintenance
Manual.
(For airplanes equipped with a Flight Warning System (FWS) speed
comparator, data from ADC #1 is compared to data from ADC #2 throughout
the flight envelope. For airplanes not equipped with a FWS speed
comparator, data from ADC #1 is only compared to data from ADC #2
during autoland and redundant operation of AFCAS. Since airplanes not
equipped with a speed comparator have a greater exposure to a hazardous
condition, a shorter compliance time is necessary.)
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect compliance
with the AD, the owner or operator is required to obtain FAA approval
for an alternative method of compliance with the AD, in accordance with
the paragraph of each AD that provides for such approvals. A note has
been included in this notice to clarify this long-standing requirement.
The FAA estimates that 119 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 29 work
hours per airplane to accomplish the proposed actions, and that the
average labor rate is $60 per work hour. Required parts would cost
approximately $4,800 per airplane. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$778,260, or $6,540 per airplane.
The total cost impact figure discussed above is based on
assumptions that no [[Page 19385]] operator has yet accomplished any of
the proposed requirements of this AD action, and that no operator would
accomplish those actions in the future if this AD were not adopted.
The regulations proposed herein would not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part 39 of the Federal Aviation Regulations (14 CFR part 39) as
follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Fokker: Docket 95-NM-29-AD.
Applicability: Model F28 Mark 0100 series airplanes, as listed
in Fokker Service Bulletin SBF100-30-015, Revision 2, dated January
25, 1995; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (c) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent icing of the No. 1 pitot tube, which could cause
failure of the No. 1 Air Data Computer (ADC) or output of erroneous
airspeed data to all on-side subsidiary systems including the
Automatic Flight Control and Augmentation System (AFCAS), accomplish
the following:
(a) Within 30 days after the effective date of this AD, perform
an operational test of the No. 1 pitot heating system, in accordance
with Part 1 of the Accomplishment Instructions of Fokker Service
Bulletin SBF100-30-015, Revision 2, dated January 25, 1995.
(1) If the pitot heating system passes the operational test,
accomplish the requirements of either paragraph (b)(1) or (b)(2) of
this AD, as applicable, at the times specified.
(2) If any pitot tube heating element is found to be
inoperative, prior to further flight, repair or replace the failed
element with a serviceable element, in accordance with Fokker 100
Aircraft Maintenance Manual (AMM).
(b) Replace the pitot head with a new pitot head, replace the
single DC current-sensing relay with two new DC current sensing
relays, and modify the electrical wiring, in accordance with Part 2
or 3, as applicable, of the Accomplishment Instructions of Fokker
Service Bulletin SBF100-30-015, Revision 2, dated January 25, 1995.
Perform these actions at the time specified in either paragraph
(b)(1) or (b)(2) of this AD, as applicable.
(1) For airplanes that are not equipped with an Flight Warning
System (FWS) speed comparator: Within 12 months or the next 3,000
hours time-in-service after the effective date of this AD, whichever
occurs first. Or
(2) For airplanes that are equipped with an FWS speed
comparator: Within 24 months or the next 6,000 hours time-in-service
after the effective date of this AD, whichever occurs first.
(c) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Standardization Branch, ANM-113,
FAA, Transport Airplane Directorate. Operators shall submit their
requests through an appropriate FAA Principal Maintenance Inspector,
who may add comments and then send it to the Manager,
Standardization Branch, ANM-113.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
(d) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
Issued in Renton, Washington, on April 12, 1995.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-9470 Filed 4-17-95; 8:45 am]
BILLING CODE 4910-13-U
